Folding staircase

ABSTRACT

A folding staircase for use in a door opening having a threshold. The folding staircase has a pair of stringers that have an upper end and a lower end that is adapted for contacting a ground surface. The stringers are spanned by at least one tread. A hinge is connected to a floor near the door opening and a threshold plate pivotally connected thereto is movable between a use position and a stowed position. The staircase may be provided with a lifting mechanism that biases the staircase and threshold plate toward their stowed positions. The lifting device provides a variable force that provides more rotational force when the staircase would require a user to bear more of its weight and less force when less of the weight of the staircase would be borne by a user.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/878,829, filed May 20, 2020, which is a continuation of U.S.application Ser. No. 16/026,517, filed Jul. 3, 2018, now U.S. Pat. No.10,662,654, which is a continuation of U.S. Utility application Ser. No.15/877,493, filed Jan. 23, 2018, now U.S. Pat. No. 10,519,671, which isa continuation-in-part of U.S. Utility application Ser. No. 15/615,102,filed Jun. 6, 2017, now U.S. Pat. No. 9,903,121, which claims thebenefit of U.S. Provisional Application Ser. No. 62/346,230, filed Jun.6, 2016, the disclosures of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Folding staircases for recreational vehicles (RVs) are necessary foreasily entering and exiting the RV. Typically, RVs which can be towableunits or motorhomes are well above the ground upon which they rest.Previous staircases to facilitate movement to and from RVs have beenunwieldy for various reasons. In some cases, steps that fold out of RVsdo not span from the RV to the ground, but remain suspended above theground. These types of steps therefore fail to provide a sturdy andconsistent path to the ground because they remain somewhat independentlyheld above the adjacent ground, which may or may not have a slope. Othersteps include multiple linkages and moving parts and only unfold withgreat effort on the part of a user. There is a need for RV steps thatrequire little effort of their user and provide a steady consistent pathto the ground upon which the RV rests.

SUMMARY OF THE INVENTION

The present invention is a folding staircase that is adapted for use ina door opening. The door opening is in a wall that has an inner wallsurface that is located within an indoor space and an outer wall surfacethat is located in an outdoor space. The door opening receives a doorthat separates the indoor space from the outdoor space.

The folding staircase has a pair of stringers that are spanned by atlast one tread. Each of the stringers has an upper edge and a loweredge, an upper end and a lower end. The lower end is adapted forcontacting a ground surface. The upper end is for abutting the outerwall surface. A hinge is adapted for being mounted to a floor within theindoor space and is spaced from the threshold. A threshold plate isconnected to the hinge. The threshold plate is pivotable between a useand a stowed position. The threshold plate has a first ramped portionthat is adapted to reach a distance that is at least the height that thethreshold is above the floor. This enables the threshold plate to spanover the threshold in its use position. The first ramped portioncontinues into a spanning portion that is adapted for directly overlyingthe threshold and spanning between the inner wall surface and the outerwall surface when the threshold plate is in its use position. Thespanning portion continues into an offsetting portion that issubstantially parallel to the outer wall surface and adjacent to thethreshold when the threshold plate is in its use position. The thresholdplate aligns the upper end of the stringers adjacent to the outer wallsurface when the threshold plate is in its use position.

In another aspect of the invention, the staircase may be provided with alifting mechanism that assists moving the staircase from its use to itsstowed position. The lifting mechanism provides a biasing rotationalforce upon the threshold plate and staircase toward the stowed position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is side view of the staircase with a sectional view through thedoor frame and floor with the staircase and threshold plate in the useposition;

FIG. 2 is a side view with a sectional view through the door frame andfloor with the staircase in FIG. 1 and threshold plate in the stowedposition;

FIG. 3 is a front view of the staircase shown in FIGS. 1 and 2 in itsstowed position;

FIG. 4 is a sectional view taken about the line 4-4 in FIG. 3 ;

FIG. 5 is a magnified view of area 5 in in FIG. 1 ;

FIG. 6 is a perspective view of the staircase shown in FIGS. 1-5 in itsuse position showing the area adjacent to the threshold;

FIG. 7 is a perspective view of a staircase with a lifting device asseen from the indoor space with the staircase in its use position;

FIG. 8 is a perspective view of the staircase shown in FIG. 7 , with thestaircase in its use position;

FIG. 9 is a perspective view of the staircase in FIGS. 7 and 8 with thestaircase between its use and stowed position;

FIG. 10 is a perspective view of the staircase in FIGS. 7-9 in thestowed position;

FIG. 11 is an exploded perspective view of the staircase shown in FIGS.7-10 ;

FIG. 12 is a side view of the staircase shown in FIG. 8 in the useposition;

FIG. 13 is a side view of the staircase shown in FIG. 9 positionedbetween its use and stowed position;

FIG. 14 is a side view of the staircase shown in FIG. 10 in its stowedposition;

FIG. 15 shows the door closed with the staircase retracted behind thedoor;

FIG. 16 shows the door open with the staircase shown in FIGS. 1-5 in thestowed position within the door opening;

FIG. 17 shows the staircase in FIG. 16 in its use position with the dooropen;

FIG. 18 shows the staircase in FIG. 17 shows the staircase of FIG. 17 inits use position with the door closed over the threshold plate;

FIG. 19 shows the staircase shown in FIGS. 6-14 in its stowed positioncompletely within the indoor space behind the door, with the door in itsclosed position as viewed from behind; and

FIG. 20 is a sectional view of the staircase in 19 with the door in itsclosed position.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The folding staircase 10 of the present invention is shown in FIG. 1 .The folding staircase 10 is for use in a door opening 16 within a wall18 that has an inner wall surface 20 that is located within an indoorspace 22 and an outer wall surface 24 that is located in an outdoorspace 26. The door opening 16 receives a door 19 that is pivotablebetween an open position showing in FIG. 16 and a closed position shownin FIG. 18 . The door opening 16 includes a door frame 17 having athreshold 27 and vertical door jambs 30 that span from the outer wallsurface 24 to the inner wall surface 20 within the door opening 16. Thejambs 30 are the vertical portions of the door frame 17 lining the dooropening 16 and are best shown in FIG. 5 and have metal door stops 31that are extensions from the jambs 30 extending along the vertical sidesof the door opening 16. The indoor space is defined by the space behindthe metal door stops 31 on which the inner surface 23 door rests whenclosed. Within the indoor space 22 a floor 35 defines the lowermostportion of the indoor space 22 and the threshold 27 rises above thefloor 35.

The folding staircase 10 has a pair of stringers 38 that are spacedparallel to each other and are spanned by treads 40. The treads 40 maybe affixed mechanically to their respective stringers 38 or welded tothe stringers 38 and in the staircase 10 shown in FIG. 5 , the treads 40are bolted to the stringers 38. Each of the stringers 38 has an upperedge 44 and a lower edge 46. The stringers 38 each have a lower end 48that includes a pivotal foot 50 that is pivotally affixed to anadjustable leg 52. In some instances having a pivotal foot 50 near thelower end is not necessary. The stringers 38 have an upper end 54 thatis adapted for abutting the outer wall surface 24. Adjacent to the upperend 54 is a truncated upper surface 56 that is perpendicular to theupper end 54 of the stringers 38. The upper end 54 is designed to beheld adjacent to and abutting the outer wall surface 24, but nottouching it. This is shown in FIG. 1 .

A hinge 60 is connected near the upper end 54 of the stringers 38 and tothe floor 35. The hinge 60 includes a floor mounting portion 64 and athreshold plate 66 that pivots about a pivot axis 67 with respect to thefloor mounting portion 64. The floor mounting portion 64 is adapted tobe mounted to the floor 35 as shown in FIG. 1 . The floor mountingportion 64 is mounted on one the side of the door 19 locating it withinthe indoor space 35. The threshold plate 66 has a first ramped portion68 that is adapted to reach upwardly to the distance the threshold 27rises above the floor 35. The first ramped portion 68 continues into aspanning portion 70 that is adapted to directly overlie the threshold 27as shown in FIGS. 1 and 6 . The spanning portion 70 has an upper surface72 and a lower surface 74. The lower surface 74 may be spaced above thethreshold 27 by a predetermined amount. This spacing above the threshold27 is shown in FIG. 5 . Spacing the lower surface 74 above the threshold27 is not required and the threshold plate 66 is designed so that thedoor 19 may be closed over the threshold plate 66 when it spans acrossthe threshold 27. The spanning portion 70 continues into an offsettingportion 78 that extends downwardly from the spanning portion 70. Theoffsetting portion 78 is adapted to be parallel to the outer wallsurface 24 and when the threshold plate 66 is in the position shown inFIG. 1 . The offsetting portion 78 continues into a mounting portion 80that is perpendicular to it. The mounting portion 80 is mounted adjacentto the truncated upper surface 56 of the stringers 38. This may beaccomplished by mechanical fasteners 82 such as bolts or rivets driventhrough lateral tabs 84 extending from the mounting portion 80. All ofthe mounting of the staircase 10 is done within the indoor space 22 ofthe vehicle and the staircase 10 requires no attachment to any part ofthe structure to which it is connected. The floor mounting portion 64 ismounted completely within the indoor space 22. In other words, noattachment is made beyond the inner wall surface 20.

The hinge 60 and staircase 10 have a use position that corresponds tothe position shown in FIGS. 1 and 6 , and a stowed position shown inFIGS. 2 and 10 . In the use position, the stringers 38 are located belowthe threshold 27, the threshold plate 66 spans the threshold 27 andextends from the indoor space 22 to the outdoor space 26. When thestaircase 10 is in its stowed position it is positioned so the staircase10 fits completely within the lateral boundaries of the door opening 16and locates the staircase 10 on the same side of the door 19 as thefloor mounting portion 64. In the stowed position, the lower edge 46 ofthe stringers 38 are located completely with the indoor space 22 and areinside the door jambs 30. In this position, the center of gravity 88 forthe staircase 10 is located inward of the pivot axis 67. As such, thestaircase 10 is biased inward. The stringers 38 have locking mechanisms90 that are located near their lower edges 46. The locking mechanisms 90have locking pins 92 that are biased outward with a spring and a stopbracket 93. Each locking pin 92 has an extended position shown in FIGS.3 and 4 and a retracted position in which the locking pin 92 isretracted within the locking mechanism 90. The locking pins 92 have aninclined surface that is adapted to strike the door stop 31 when thestaircase 10 is moved from its use position to its stowed position andthis pushes the locking pins 92 inward to clear the door stops 31. Oncethe locking pins 92 pass the door stops 31 they extend behind it asshown in FIG. 5 to lock the staircase 10 in place. The locking pins 92may be retraced by twisting a handle 96 that pulls on release linkages97, which retract the pins 92. When the staircase 10 is in its stowedposition it is biased to rest upon the stop brackets 93 that prevent thestaircase 10 from falling inward.

The folding staircase 10 may also be assisted through the use of alifting device 98 that reduces the force necessary to move the staircase10 from its use position to its stowed position. The lifting device 98is shown in FIG. 7 as viewed from the indoor space. The lifting device98 has a cover 100 that is shown removed in FIG. 8 . In the embodimentshown in FIGS. 6-11 , a threshold plate 102 has a first hinge flange 105and a second hinge flange 106. The first and second hinge flanges 105,106 are positioned such that they extend beyond the door jambs 30 andobstruct no portion of the door opening 16. The hinge flanges 105, 106define the ends of the threshold plate 102. The threshold plate 102pivots about pivot axis 104 that acts as a hinge for the threshold plate102 and the pivot axis 104 is defined by the central axis of two bolts108 extending through the hinge flanges 105, 106 of the threshold plate102. The bolts 108 also extend through corresponding opposing first andsecond hinge flanges 118 and 122 on first and second mounting brackets110, 112 that are affixed within the indoor space 22. The first andsecond mounting brackets 110, 112 function as the floor mounting portion64 and the mounting brackets 110, 112 are mounted completely within theindoor space 22. The first and second mounting brackets 110, 112cooperate with the threshold plate 102 to function as a hinge thatpivots about axis 108. The first mounting bracket 110 is shown on theleft side in FIG. 8 and the second mounting bracket 112 is shown on theright side. The mounting brackets 110, 112 have corresponding wallmounting flanges 120 and 121. The first wall mounting flange 120 isperpendicular to the first hinge flange 118 on the first mountingbracket 110. The second wall mounting flange 121 is perpendicular to thesecond hinge flange 122 on the second mounting bracket 112. Eachmounting bracket 110, 112 has a floor flange 123, 125 that is forfastening the mounting brackets 110, 112 to the floor 35. On the firstmounting bracket 110, the first wall mounting flange 120, first hingeflange 118 and first floor flange 123 are all perpendicular with respectto each other and are all joined to form a rigid corner 127. On thesecond mounting bracket 112, the second wall mounting flange 121, secondhinge flange 122 and second floor flange 125 are all perpendicular withrespect to each other and are joined to form a rigid corner 129. Assuch, the mounting brackets 110, 112 are extremely rigid yet lightweight.

Each mounting flange 110, 112 has an inner edge 131, 132 and an outeredge 133, 135 respectively. Each hinge flange 118, 122 extends from theouter edge 133, 135 of its corresponding wall mounting flange 120, 121.As such, the mating hinge flanges 105, 106 of the threshold plate 102are maintained offset from the door jambs 30 because the inner edges 131and 132 are typically aligned with or slightly inset from the edges ofthe door opening 16. In other words, the inner edges 131, 132 areslightly inset or aligned with the door jambs 30. The hinge flanges 105,106 of the threshold plate 102 are located between the inner edges 131,132 and outer edges 133, 135 of the wall mounting flanges 120, 121. Thethreshold plate 102 spans across the threshold 27 to the outdoor space26 and is joined to the stringers 38 near the upper ends 54 of thestringers 38. The pivot axis 104 extends through both hinge flanges 105,106 so that the threshold plate 102 can pivot with respect to the doorframe 17 and the pivot axis 104 is fixed with respect to the door frame17. The hinge flanges 105, 106 of the threshold plate 102 pivotally ridebetween the hinge flanges 118, 122 on the mounting brackets 110, 112.The hinge flanges 118, 122 on the mounting brackets 110, 112 pivotallyretain the entire threshold plate 102. Because the hinge flanges 105,106 of the threshold plate pivot between the hinge flanges 118, 122 ofthe mounting brackets, the threshold plate 102 is restrained from axialmovement while allowing it to pivot about the pivot axis 104. All of themounting of the staircase 10 via the mounting brackets 110, 112 is donewithin the indoor space 22 of the vehicle and the staircase 10 requiresno attachment to any part of the structure to which it is connected. Noattachment is made beyond the inner wall surface 20.

A pair of gas springs 126 are connected between the second hinge flange122 of the second mounting bracket 112 and the second hinge flange 106of the threshold plate 102. The gas springs 126 straddle the secondhinge flange 122 on the second mounting bracket 112 and the hinge flange106 on the threshold plate 102. The gas springs 126 exert a force in adirection that extends their length. The gas springs 126 have a firstend 128 pivotally connected at pivot point 130 located on the secondhinge flange 122 of the second mounting bracket 112. This pivotallyfixes the first end 128 and pivot point 130 with respect to the dooropening 16. The gas springs 126 have a second end 134 pivotallyconnected at pivot point 136 on second hinge flange 106 of the thresholdplate 102. Pivot point 136 is pivotally fixed with respect to the secondhinge flange 106 on the threshold plate 102. Thus, the second end 134and pivot point 136 move with respect to the door opening 16 as thethreshold plate 102 pivots. The gas springs 126 work well for providinglifting assistance in the present invention because they have arelatively flat force curve when compared to other springs such as coilsprings. Because the gas springs 126 straddle the hinge flanges 122 and106, they do not exert a bending force on the flanges 122, 106 to whichthey are connected. Each spring 126 exerts a force along its line ofaction 140 that acts through the pivot points 130, 136. FIG. 12 showsthe staircase 10 in its use position in which the pivotal feet 50contact the ground. In the use position, the line of action 140 of thegas springs 126 is relatively near the pivot axis 104 of the thresholdplate 102. The distance of the line of action 140 from the pivot axis104 is shown as D1 in FIG. 12 . When the line of action 140 isrelatively near the pivot axis 104, the gas springs 126 do not exert arelatively strong moment on the staircase 10 via the threshold plate102, and thus, the assistance to the user is relatively light. In theuse position, the center of gravity 88 is relatively near the outer wallsurface 24 and a large amount of assistance is not needed because a userdoes not bear a large portion of the weight of the staircase 10. As thestaircase 10 is moved between the use and stowed position to a positionwhere the staircase 10 is approximately perpendicular to the outer wallsurface 24, the center of gravity 88 is at its farthest from the outerwall surface 24 and a user of the staircase 10 will bear a large portionof the weight to of the staircase 10. This position is shown in FIG. 13. In this position, the line of action 140 is relatively far from thepivot axis 104 of the threshold plate 102 and this provides a relativelyhigh amount of assistance because the springs 126 generate a relativelylarge moment about the pivot axis 104 that urges the staircase 10towards its stowed position. Hence the springs 126 are able to generatea large amount of assistance when a user of the staircase 10 would bearthe most weight during lifting it. The distance between the line ofaction 140 and the pivot axis 104 when the staircase 10 is between itsuse and stowed positions is shown as D2 in FIG. 13 . Distance D2 is thelargest distance that the line of action 140 is from the pivot axis 104and coincides with the position of the staircase 10 when the center ofgravity 88 is farthest from the wall 18. Thus, the line of action 140moves farther from the pivot axis 104 as the staircase 10 is rotatedfrom its use position toward its stowed position for a portion of thepivotal movement. As the staircase 10 is further lifted towards itsstowed position, again the line of action 140 moves relatively nearerthe pivot axis 104. The relationship between the line of action 140 andthe pivot axis 104 in the stowed position is shown as D3 in FIG. 14 . Assuch, relatively little biasing rotative force is provided near thestowed position because assistance is not needed. As shown in FIG. 2 ,the center of gravity 88 will be inside the door frame 17, and in thecase of the staircase 10 shown in FIGS. 6-11 , the center of gravity 88will be farther from the inner wall surface 20 than the pivot axis 104of the threshold plate 102. As such, the staircase 10 will be biasedinwardly under its own weight to rest on its stop brackets 93 as shownin FIG. 4 . When the staircase 10 rests on its stop brackets 93, the gassprings 126 are designed to exert no biasing force. As such, in theevent the gas springs 126 need to be changed, they may be easily removedwithout any need to compress the gas springs 126 to facilitate theirremoval. Throughout the entire movement of the threshold plate 102 fromits use to stowed position, the gas springs 126 remain contained betweenthe second hinge flange 106 on the threshold plate 102 and the hingeflange 122 on the second mounting bracket 112. Due to the fact that thehinge flanges 106 and 122 remain in the indoor space 22 at all timesbehind the inner wall surface 20, the gas springs 126 remain in theindoor space 22 at all times.

When a user of the staircase 10 shown in FIGS. 6-11 is ready to storethe staircase 10, he will lift up near the lower end 48 of thestaircase. As the staircase 10 is lifted, the gas springs 126 providemore assistance as the line of action 140 shifts from its relativelynear position to the pivot axis 104 shown in FIG. 8 to its relativelyfar position shown in FIG. 9 . The user of the staircase 10 will receivethe most assistance when the staircase 10 is in the position shown inFIGS. 9 and 13 . As such, the user of the staircase 10 will need toexert a relatively low and nearly constant force as the staircase 10 ismoved from its use position to its stowed position.

The folding staircase 10 and lifting device are designed so that no partof the lifting device is within the door opening 16. In other words, noparts of the mounting brackets 110, 112 and the parts affixed theretoprotrude within the space between the door jambs 30. This can be seen inFIGS. 6 and 7 . Thus, the path through the door opening 16 isunobstructed by any parts of the staircase 10.

In the use position of the staircase 10, the threshold plate 102extending to its inner edge 142 covers the mounting flanges 123, 125 andthe cover 100 covers the lifting device 98 as shown in FIG. 7 .Laterally, the threshold plate 102 covers the floor mounting flanges123, 125 of the mounting brackets 110, 112 because the hinge flanges105, 106 of the threshold plate 102 pivotally ride along the insides ofthe hinge flanges 118, 122 of the mounting brackets 110, 112.

Thus, most of the mounting hardware and working parts associated withlifting the staircase 10 remain hidden with respect to a user of thestaircase 10.

The working parts of the staircase 10 are designed to allow operation ofthe door 19 when the staircase 10 is in either its use or stowedposition. In FIG. 16 , the staircase 10 is shown in its stowed position.With the door 19 open, and with the door 19 remaining open, thestaircase 10 may be moved to its use position shown in FIG. 17 . Oncethe staircase is in its use position, the door 19 may be closed over thethreshold plate 66 as shown in FIG. 18 . The staircase 10 shown in FIGS.16-18 uses the unassisted threshold plate 66 as shown in FIGS. 1-5 . Inthe same way, the staircase shown in FIGS. 6-14 that is assisted allowsthe door 19 to close when the staircase 10 is in both its use and stowedposition. FIG. 19 shows the door 19 closed over the threshold plate 102from the indoor space 22 with the staircase and threshold plate 102 intheir use position. FIG. 20 shows the staircase 10 in its stowedposition with the door 19 in its closed position with the entirestaircase and threshold plate 102 being located on the same side of thedoor as the mounting brackets 110, 112.

It is understood that while certain aspects of the disclosed subjectmatter have been shown and described, the disclosed subject matter isnot limited thereto and encompasses various other embodiments andaspects. No specific limitation with respect to the specific embodimentsdisclosed herein is intended or should be inferred. Modifications may bemade to the disclosed subject matter as set forth in the followingclaims.

What is claimed is:
 1. A staircase comprising: a pair of stringersspanned by one or more treads; a lower end adapted for contacting aground surface and an upper end opposite the lower end; and a hinge ofthe upper end, the hinge comprising: a floor mounting portion that isadapted to be mounted on a floor; and a threshold plate having a firstend and a second end opposite the first end, the first end coupled tothe floor mounting portion and pivotable with respect thereto about apivot axis and the second end coupled to the upper end; wherein thestaircase has a stowed position and a use position rotationally offsetfrom the stowed position, and, when in the stowed position, thethreshold plate is positioned above the floor mounting portion with acenter of gravity of the staircase disposed rearwardly of the pivot axisto bias the pair of stringers rearwardly.
 2. The staircase of claim 1,wherein, when in the stowed position, the threshold plate is positionedvertically above the floor mounting portion.
 3. The staircase of claim1, wherein, when in the use position, the threshold plate and floormounting portion form an obtuse angle.
 4. The staircase of claim 1,wherein the pivot axis is configured to be located above the floor. 5.The staircase of claim 1, wherein the staircase is adapted to fit withina door opening and is prevented from falling towards the use positionwhen in the stowed position.
 6. The staircase of claim 5, wherein thepair of stringers each include an upper surface and a lower surface, andthe staircase is configured to be biased rearwardly in the stowedposition such that the lower surface is disposed rearwardly of aninterior surface of a wall of the door opening.
 7. The staircase ofclaim 5, further comprising a releasable lock configured to engagestructure of the door opening to retain the staircase in the stowedposition.
 8. The staircase of claim 7, wherein the lock comprises a pairof retractable pins coupled to the pair of stringers.
 9. The staircaseof claim 8, further comprising a linkage coupled to the pair ofretractable pins and a handle coupled to the linkage, the handleconfigured to be manipulated to release the lock via the linkage. 10.The staircase of claim 8, wherein the pair of stringers each include anupper surface and a lower surface, and the pair of retractable pins aremounted to the lower surfaces of the pair of stringers.
 11. Thestaircase of claim 10, wherein the pair of retractable pins are mountedto the lower surfaces of the pair of stringers with adjustable brackets.12. The staircase of claim 1, wherein the lower end includes at leastone adjustable leg.
 13. The staircase of claim 12, further comprising afront side accessible to the user and a backside opposite the frontside, the at least one adjustable leg being coupled to the front side.14. The staircase of claim 12, wherein the at least adjustable legincludes at least one pivotable foot.
 15. A staircase comprising: a pairof stringers spanned by one or more treads, the pair of stringers eachextending along an axis; a lower end adapted for contacting a groundsurface and an upper end opposite the lower end; and a hinge coupled tothe upper end, the hinge comprising: a floor mounting portion that isadapted to be mounted on a floor, and a threshold plate having a firstend and a second end opposite the first end, the first end pivotallycoupled to the floor mounting portion and the second end coupled to theupper end; and at least one adjustable leg coupled to the lower end, theat least one adjustable leg extending along the axis of the pair ofstringers; wherein the staircase has a first position and a secondposition rotationally offset from the first position, and when in thefirst position, the at least one adjustable leg is configured to contactthe ground surface.
 16. The staircase of claim 15, wherein the at leastone adjustable leg comprises a pair of adjustable legs coupled to thepair of stringers.
 17. The staircase of claim 16, wherein the pair ofstringers each have an upper surface and a lower surface extendinggenerally parallel to one another, and the pair of adjustable legsextend generally parallel to the upper and lower surfaces.
 18. Thestaircase of claim 16, wherein an outer surface of each of the pair ofadjustable legs is co-planar with an outer surface of the pair ofstringers, respectively.
 19. The staircase of claim 15, furthercomprising a front side and a backside opposite the front side, the atleast one adjustable leg being coupled to the front side.
 20. Thestaircase of claim 15, wherein the at least one adjustable leg includesat least one pivotable foot.
 21. The staircase of claim 20, wherein,when the staircase is in the second position, the threshold plate ispositioned vertically above the floor mounting portion.
 22. Thestaircase of claim 15, wherein the threshold plate pivots around a pivotaxis that is configured to be located above the floor.
 23. The staircaseof claim 15, wherein, when the staircase is in the second position, thestaircase is adapted to fit within a door opening and is prevented fromfalling in a direction opposite to the first position.